Sources of systematic error in gravitational-wave measurements of the binary neutron star mass distribution

The binary neutron star mass distribution measured with gravitational-wave observations has the potential to reveal information about the dense matter equation of state, supernova physics, the expansion rate of the universe, and tests of General Relativity. Most analyses of the growing population of observed binary neutron star mergers neglect the impact of the assumed neutron star spin distribution on the inferred mass distribution. We demonstrate that neglecting a poorly chosen spin distributions can seriously impact the inferred mass distribution and lead to false inferences about the most extreme neutron stars.